The framing of buildings for residential and commercial construction has traditionally been accomplished using suitably dimensioned wood members. While the use of wood members makes the construction relatively simple, the use of wood members has its shortcomings. The supply of lumber is getting scarcer and costs have increased during recent years. In addition wood can warp and go out of shape when it becomes wet as well as being susceptible to attack by vermin of various kinds including termites.
In recent years buildings framed with sheet metal framing members have been employed. The use of sheet metal framing members provides advantages of dimensional stability, ease of manufacture and conservation of natural resources among others. However the use of sheet metal members, particularly, joists has not gained widespread acceptance for various reasons. One such reason is that the ends of the joists where they are attached to a vertical wall require that they be securely attached to the rim joist and that they be provided with some reinforcement to provide the joist with the capability of supporting the load at the ends. In the past this has commonly been accomplished by using an L shaped bracket of a height about equal to the web of the joist. One leg of the bracket is attached to the web at the end of the joist and the other leg is attached to the web of the rim joist. Another solution employs a section of steel stud or track equal in height to the height of the joist web. The web of the stud or track section is attached to the web of the joist and one flange of the stud is attached to the web of the rim joist. A variation on this is shown in U.S. Pat. No. 5,625,995 issued May 6, 1997 to Byron Martin. This patent describes a special bracket shaped like a stud section for attaching this joist to the header. While these solutions provide the required attachment and reinforcing for the floor joist, they significantly increase the labor time required to install the steel joist system. Consequently steel joist systems have not gained widespread acceptance among the framing trades.
A modified ledger or rim joist has recently been described in U.S. Pat. No. 5,956,916 issued Sep. 18, 1999 assigned to Steel Floor Ltd. in an attempt to overcome the above problems. The web of the ledger is provided with struck out tabs which extend perpendicularly inwardly of the web at a regular spacing, typically 16 inches on center. The tabs act as a locating means and attachment means for the floor joist as well as reinforcing the end of the web of the floor joist. While the modified ledger joist makes the attachment of the floor joist easier, it also introduces new problems. The alignment of the ledger must be closely controlled so that the floor joists spanning the space between the ledge will be properly aligned with the struck out tabs. This will require additional labor time by the framing trades. Additionally, as the location of the tabs are fixed at the time of manufacturing of the ledger, the flexibility in the spacing of the floor joists is limited. In some cases such as to avoid a service stack or to provide additional support below partition walls, it may be necessary to adjust the spacing of the floor joist or to install additional joists. In addition if the load characteristics change, the joist spacing required to support the load may change. Another situation where the floor joists will not properly align with the tabs is if the floor joist meets the ledger joist at other than right angles, e.g. 45 degree angles commonly encountered in bay window bump outs. In those cases, another means for providing the attachment and reinforcing of the end of the joist would be required such as the bracket or stud section described above, thus defeating the advantages of the modified rim joist.
There thus still remains a need for an easy to install means of attaching a steel framing members such as a steel joist to a supporting framing member such as a rim joist and reinforcing the end of the framing member.